Additional information on the accretion variability of RU Lup can be obtained by measuring the excess emission in photospheric lines (veiling), as described in Eq. REF . The excess emission in a given line is the sum of the continuum emission from the accretion shock at the line wavelength and of the emission of the same line in accreting matter [1]}. By measuring the amount of veiling in a CTTS, it is possible to quantify the amount of accretion activity occurring in the star during a given observation.
